The present invention relates to a method for processing non-pasteurized grape juices to prepare soft wines.
The invention also relates to a soft wine product prepared by the inventive method.
A soft wine is a non alcoholic wine which is at present considered as a valued beverage by all persons taking lunches or dinners or participating to parties who, as it is well known, must necessarily reduce to a minimum the use of alcohol in order to prevent all problems related to alcohol consume in driving a car during a return trip, both to prevent road accidents from occurring and not to be subjected to serious legal and police measures in a case of possible controls.
In particular, the inventive method allows to process any type of grape juice cocktail products, by performing a specifically designed radiofrequency (RF) treatment causing in said cocktails a microbic deactuation in absence of any thermal effects.
The existence of a non thermal effect related to the inventive method allows to sanitize grape juice products, without altering in any manners their nourishing properties.
In the inventive method, RF waves are used for stabilizing an analcoholic grape juice aromatized cocktail.
The high frequency radio wave processing step of the inventive method allows to sterilize an aromatized soft cocktail of wine products requiring said wine products to be bottled in aseptic bottles and environments.
A further feature of the inventive method is that the grape juice based products are processed by E242.
This non thermal treatment of the inventive method allows to sanitize the grape juice based products without altering their qualities and nourishing properties.
This is the first application of a E242 treatment to a grape juice aromatized cocktail, and, in this case, it is not necessary to perform a radiofrequency aseptic bottling.
A further feature of the inventive method consists of a stripping step which will be disclosed in a more detailed manner hereinafter.
This stripping step is performed by a gaseous washing, by food grade nitrogen, of the grape juice products, and, more specifically, said stripping step comprises a transferring of a gas (oxygen) dissolved in a liquid (wine must) from a liquid phase (the wine must) to a gaseous phase (air).
This must oxygen reduction is carried out before a sparkling or aromatizing step thereby greatly reducing dissolved oxygen while simultaneously reducing product oxidation effects, to greatly increase the product shelf-life time.
Another very important step of the inventive method consists of a pressing/grape stalk removing and decanting of the product, in absence of any contacts with oxygen.
With respect to the radiofrequency (RF) treatment, although this processing step has been hereinabove generally disclosed, it will be further disclosed in a more detailed manner hereinafter by way of an illustrative but not limitative example of one of several embodiments of using the inventive method, to make an analcoholic sparkling wine having the same taste and organoleptic characteristics as those of an alcoholic conventional “prosecco” wine, thereby allowing the inventive analcoholic prosecco wine to be freely consumed, even before driving a car, as a very good beverage in lunches, dinners, parties and so on.
The method according to the present invention has been specifically designed for making a novel sparkling soft prosecco wine, which is, from a taste standpoint, perfectly like a traditional prosecco.
Pasteurized grape juices and de-alcoholated wines are already known on the market.
A conventional industrial method for providing prior grape juices comprises a first step of mechanically picking up grapes and separating the grapes from other components such as grape stalk and shells.
Then the thus processed prior grape juices are added with a very high dose of sulphurous anhydride, also larger than 3000 mg per liter, to prevent any alcoholic fermentation from occurring.
The wine must is thereby hold, during the overall collection period, in a standby condition for subsequent processing operations which comprise, at first, a sulphur removal, performed in large vacuum operating systems, in which sulphurous anhydride is removed up to provide very low residual values thereof (0-20 mg/liter).
Then, the grape juice is further processed by yeasts and the wine must is immediately directed to the subsequent processing step, comprising a pasteurizing thereof.
As it is known, pasteurizing is a thermal treatment, usually performed at a temperature less than 100° C., and is designed for biologically stabilizing the product by a deactuation of microbic and enzymatic actions.
Such a pasteurizing allows to extend the life of products such as fruits and grape juices, that is extend their “shelf life”, by several months.
In the pasteurizing treatment, no temperature sufficient to devitalize thermophyl microorganisms and spores is achieved.
Accordingly, the pasteurized juice is preferable under conditions adapted to limit a development of the above microorganisms.
In other words, pasteurizing is conventionally associated with other like preserving systems, such as the use of sulphurous anhydride or other preserving agents or a storing in a sterile environment.
The duration of the above pasteurizing treatment varies depending on the method type, also depending on the nature of juices and their contamination degree.
It is possible to carry out high speed treatments at higher temperature or longer treatments at lower temperatures.
The pasteurizing of grape juices and must has greatly negative organoleptic consequences such as the Maillard's reaction, also known as a non enzymatic darkening effect, which occurs as the grape must, in which sugars and aminoacids are present, is subjected to a thermal treatment.
The Maillard's reaction causes, as it is well known, a formation of oxymethylfurfural (OMF) greatly altering aroma, taste and color of the wine must.
Then, the product is stored in an aseptic environment: the must, from which fermentative agents have been removed, is then prevented from achieving an alcoholic fermentation by at first preserving it in sterilized tanks (sterilized by steam or chemical substances).
The exposition to air and low levels of sulphurous anhydride, however, negatively affects the wine must organoleptic quality.
Finally, juices are recovered from the storing tanks and packaged in an aseptic environment, in which condition they are sent to selling.
Conventional grape juice based industrial products do not preserve their original organoleptic high quality, since the treatments the juices are subjected to cause a modification, such as a disappearing, removal or deterioration of the starting must perfume/taste, and, in a lot of cases, also alter the must color because of the above mentioned Maillard's reaction and oxidation of must phenolic components.
Thus, to make satisfactory grape juices it is absolutely necessary to use, depending on the raw material type, its ripening degree and so on, aromas to restitute some original organoleptic properties starting product.
With respect to de-alcoholated wines, CE regulation No. 606/2009 has introduced, as an admitted oenological practice, a partial dealcoholation of wines by means of physical methods.
A full elimination of alcohol is thereby not allowed.
The above dealcoholation methods are broadly used in several food and chemical industrial areas, such as in beer dealcoholation, and in a lot of other agroalimentary sectors.
The reduction of the alcoholic titre of wines may be achieved by a corresponding reduction of the sugar contents of must or a partial dealcoholation of wine.
The dealcoholation method is legally allowed from some years in several Countries, but not in the European Union, and is carried out by systems based on the so-called membrane techniques, by which the reduction of the wine alcohol contents is achieved by removing ethyl alcohol or reducing the sugar contents, said sugar contents reducing being performed by a combination of ultrafiltering and nanofiltering steps, in which a portion of an ultrafiltered must is concentrated by an osmotic nanofiltering membrane: the retentate, rich in sugars, is separated from must, whereas the permeate, rich in acids, is reintegrated to the must, which, in this manner, will have reduced alcoholic contents.
This method, proposed by Swiss research workers, is comparatively expensive and complex from a technical standpoint, and provides organoleptic results which are at present still object of studies.
With respect to the must dealcoholizing methods, among the physical methods directly applied on must to cause alcohol to be evaporated at low temperature, the so-called “Spinning Cone Column”, already applied to beer dehalcoholizing, is herein mentioned, which spinning cone column comprises a vertical stainless steel cylinder in which an inert gas having a stripping effect, removes, under vacuum, a volatile compound stream or current from liquid.
The above spinning cone column method is a very efficient method, and moreover has a good energetic efficiency.
The disadvantage of this method is the heating of the must mass, necessary for providing dealcoholizing, since the stripping step is performed at 38° C., with a consequent organoleptic decay of must.
By means of product fractionation processes, it is possible to remove alcohol from wines by using osmotic membranes in combination with a permeate evaporation.
One of these techniques provides to use a combination of a reverse osmosis and distillation, (which is a technically feasible and inexpensive method), in which a hydrophilic osmotic membrane is used.
In this method, must is subjected to a reverse osmosis to produce a permeate which is dealcoholated by distillation and then being reintegrated to the reverse osmosis retentate.
The above is a subtractive method involving a negligible decrease of the product volume and a possible reduction or decay of volatile compounds characterizing the main must olfactory properties.
Yet another method is that of processing must by hydrophobic membranes which are interposed between the must and an extracting solution or water, to provide a gas film (a gaseous membrane) therethrough the more volatile compounds will pass, the most representative of which is ethanol.
This technology, called “a contactor method”, does not perform any must fractionation but a non negligible reduction of the must volume and volatile compounds.
The reverse osmosis method, in combination with distillation, has been already used in several Countries with the exception of the European Union.
A partial wine dealcoholation is broadly diffused in some viticultural areas such as California; however, the operating steps generally pertain to conventional methods affected by several critical problems, even from a qualitative standpoint.
As exposed on Jun. 26, 2010 by the vice-chairman of OIV (“Organisation Internationale de la Vigne et du Vin”), Peter Hayes, during an OIV general meeting, data on the sensorial effect of dealcoholation show that great differences exist with respect to the starting product thereby suggesting a possible refining of this technology to further reduce the alcohol contents and produce less adverse effects on the product sensory properties.